/*
 * Copyright (c) 2008, Sun Microsystems, Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * 
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * * Neither the name of Sun Microsystems, Inc. nor the names of its contributors
 *   may be used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package jsf.util;

/**
 *
 * @author mbohm
 */
public class PagingInfo {
    private int batchSize = 5;
    private int firstItem = 0;
    private int itemCount = -1;
    
    public int getBatchSize() {
        return batchSize;
    }
    
    public int getItemCount() {
        return itemCount;
    }
    
    public void setItemCount(int itemCount) {
        this.itemCount = itemCount;
    }
    
    public int getFirstItem() {
        if (itemCount == -1) {
            throw new IllegalStateException("itemCount must be set before invoking getFirstItem");
        }
        if (firstItem >= itemCount) {
            if (itemCount == 0) {
                firstItem = 0;
            } else {
                int zeroBasedItemCount = itemCount - 1;
                double pageDouble = zeroBasedItemCount / batchSize;
                int page = (int) Math.floor(pageDouble);
                firstItem = page * batchSize;
            }
        }
        return firstItem;
    }
    
    public void setFirstItem(int firstItem) {
        this.firstItem = firstItem;
    }
    
    public int getLastItem() {
        getFirstItem();
        return firstItem + batchSize > itemCount ? itemCount : firstItem + batchSize;
    }
    
    public void nextPage() {
        getFirstItem();
        if (firstItem + batchSize < itemCount) {
            firstItem += batchSize;
        }
    }
    
    public void previousPage() {
        getFirstItem();
        firstItem -= batchSize;
        if (firstItem < 0) {
            firstItem = 0;
        }
    }
}
